The present invention relates to a medium for embedding cells and tissues containing native DNA and/or native RNA to preserve its structure when stored. The present invention also relates to a method of using the embedding medium for protecting native DNA/RNA destined for use in DNA/RNA amplification, in particular by PCR and RT-PCR.
High copy numbers of specific nucleic acid sequences (fragments) may be obtained from DNA by amplification using the polymerase chain reaction (PCR) or from RNA using the reverse transcriptase polymerase chain reaction (RT-PCR). For details about the PCR, see PCR, A Practical Approach, McPherson, Quirke, and Taylor, Eds. IRL Press, Oxford 1991.
Quantitative PCR and RT-PCR are used in assaying pathological conditions of cells and tissues, such as the presence of pathogenic microorganisms and genetic mutations causing malignancy, for instance malignancy in lymphocytes isolated from patients suspected to suffer from lymphoma, for instance, T- or B-cell lymphoma or Hodgkin""s disease. Most often cells and tissue sampled for this reason cannot be assayed on the spot but need to be stored for a certain period of time prior to being assayed. It is important that the DNA be preserved in its native state during such storage. The problem of storage is not a minor one since it has been reported (G R. Turbett and Loryn N. Sellner, Diagn. Mol. Pathol. 6(5):298-303, 1997) that preservation of frozen tissue in a widely used embedding medium, Optimal Cutting Temperature(trademark) (OCT) may inhibit PCR and RT-PCR. xe2x80x98Native DNAxe2x80x99 and xe2x80x98Native RNAxe2x80x99 designate native DNA/RNA in a tissue sample as well as isolated native chromosomal DNA/RNA, and sequences thereof.
It is an object of the invention to provide a medium of the aforementioned kind preserving DNA/RNA in its native state for extended periods of time.
It is another object of the invention to provide a method of using a medium in the preservation of native DNA/RNA in cells and tissues destined for use in DNA/RNA amplification methods.
Further objects of the invention will become apparent from the study of the following summary of the invention, the description of preferred embodiments thereof, and of the appended claims.